Nowadays, motors of electric vehicles commonly both have a driving function and a regenerative braking function. The regenerative braking function is that an accelerator of an vehicle is released or the vehicle is braked, the vehicle drives the motor because of inertia and kinetic energy of the vehicle is converted into regenerative energy for a battery of the vehicle by switching drivers of the motor. In a typical regenerative braking controlling method based on an magnetic field oriented control, when regenerative current is beyond a preset current value, mechanical energy generated from the braking is consumed by resistors of motor so that regenerative braking efficiency is relative lower.